Bioinformatics analysis
The function annotation and classification of the identified DEPs were
performed based on Gene Ontology (http://www.geneontology.org/) and
Uniprot (http://www.uniprot.org/)
databases.25,26Subcellular location prediction analysis was conducted with WoLF PSORT
tool
(http://wolfpsort.org/).27The hierarchical clustering analysis of the protein expression profiles
under different Ca levels was performed referring Hu et
al.28 Fold changes of
protein abundances were calculated by dividing the density value of DEPs
at low Ca level or high Ca level by that at media Ca level. The resulted
values were log2 transformed and inputted into the Cluster software
(version 3.0) with complete linkage algorithm setting. The hierarchical
cluster results were visualized with TreeView software version 1.1.3.
For PPI network construction, the STRING database and Cytoscape software
was used.29